I need help with my assignment please

Compute the payback period for each of these two separate investments a. A new operating system for an existing machine is expected to cost $290,000 and have a useful life of six years. The system yields an incremental after-tax income of $83,653 each year after deducting its straight-line depreciation. The predicted salvage value of the system is $11,000. b. A machine costs $180,000, has a $15,000 salvage value, is expected to last eight years, and will generate an after-tax income of $46,000 per year after straight-line depreciation. Payback Period Choose Denominator: Choose Numerator: Payback Period Payback period